Field of the Invention
This invention relates to a heatable sheet assembly and, more particularly, to a heatable sheet assembly which can be cut to any desired shape and which posesses, above all, heat storage capabilities.
In the prior art, there are a variety of proposals with respect to a heatable sheet assembly containing carbon fibers and adapted to be utilized in, for example, floor heaters, horticultural equipments, bedding, health appliances or cattle sheds. For example, there is disclosed in Japanese Laid-open Patent Publication No.18702/1975 a paper-like composition containing acrylonitrile type synthetic resin pulp and carbon fibers. There is also disclosed in Japanese Laid-open Patent Publication No.281293/1987 a heatabale sheet obtained by mixing carbon fibers and natural pulp by the paper making technique.
The conventional heatable sheet assembly has, however, a drawback that, since the electodes are mounted on its opposite sides on the same planar surface, it cannot be formed into, for example, a doughnut shape, although it can be formed into a quadrangle such a square or rectangle, and thus the shape of the heatable sheet assembly itself is restricted.
The conventional heatable sheet assembly has also a drawback that, since the electrodes are mounted on the same planar surface, the electrodes are spaced apart from each other, with the result that the electrical resistance of the heatable sheet assembly between the electrodes is increased and hence the stable electrical resistance and temperature characteristics in the heatable sheet assembly can be obtained with considerable difficulties.
In addition, there lacks up to now a heatable sheet assembly provided with electrodes that is endowed not only with the function of heat storage but also with the function of radiating far infrared rays.